Nothing to fear but fear itself.

 Let me start by saying I love my Webasto Dual Top. It is a Diesel fired furnace and hot water tank. The concept is great, a combo unit that provides heat and water and runs off of the same fuel source as the bus. Making fuelling up the unit, a one stop shopping deal.
That being said, I have been fraught with challenges as of late, which all came from a water leak. Now I could blame the design engineers for putting the water inlet directly above some of the system electronics, so that a leak would fry a mother board, then some of the delicate 20 gauge wires leading to the water overheat sensor can easily become damaged when you take apart the furnace yourself because you can't find a webasto service centre willing to work on this model of furnace. I could say all that but I wont, that would be childish and petty.

Instead I will expound on how I thoroughly enjoy online shopping and shipping. Although I cannot find any help in Calgary with this unit. I am able to find parts and advice internationally! And they ship to my door. So after replacing the furnace blower (water damage) and the hot water sensor (technician error) I was ready to reinstall  the furnace. But....(queue the sombre foreshadowing music)
before I did, I decided it was time to right a previous wrong. This past spring I installed the Webasto X100 cooktop. Unfortunatley I had a few issues with the install process, first the electrical then the fuel line. As according to instruction, I spliced into the return fuel line from the engine and ran a fuel line to the cooker. My issue was that the fuel line I used was a 3/32 I.D. Which was difficult to find off the shelf. The line that I found was a soft sided line (blue line attached to the side wall in the photo) that I wasn't convinced was going to cut the mustard. But we tried....and it failed. So Again, I had a Webasto fuel line kit sent to me, and it sat in wait in my shop waiting for the right moment to strike. And this was the moment.

So while I was under there I ran the right fuel line, using the correct filter, and fished it up to the cooker to be connected at a later date when I have time to putter and drink coffee.(insert dramatic suspenseful musical crescendo) -camera pan across and zoom in on the text "to be connected at a later date"

After recruiting Anna to help me lift and hold the furnace into place, the electrical hook ups were completed , fuel line attached and .........Notta....No Go....epic fail....
The furnace would start up, the exhaust would get warm indicating the start of combustion and then....shut down and error code. The error code indicated there was a no fire/fuel problem. with each possible avenue for error things checked out. I then got it down to the fuel pump. I wanted to test and make sure the fuel lines were drawing the appropriate amount of fuel and that the pump was working properly. I disconnected the fuel line in between the  pump and the fuel filter. and I found good news and bad. The bad new was, I couldn't get a good bleed on the fuel line. Every time I put the inline pump on the line it would suck up a whack of air.

The good news was when I placed a direct fuel line into a separate fuel source, the furnace fired right up(after two attempts). I had to take a break to cook dinner, which gave me time figure out how this could be a problem now where it never has been before? The $64,000 question was..."what has changed?"

 (flash back to installing the new X100 fuel line, and the sentence " to be connected at a later date")
I essentially created my own problem. The open fuel line to the cook top was allowing the fuel pump for the furnace (which is attached to the same fuel tank pick up as the return line from the engine) to suck up air. Thus no fuel error code. A simple crimp of the open line, bleed the line to the furnace and we have heat!